.panel {
  position: absolute;
  left: 0;
  top: 0;
  margin: 50px;
  padding: 5px;
  border: 1px solid #eee;
}
.panel::after {
  content: "";
  display: block;
  clear: both;
}
.hue {
  position: relative;
  width: 200px;
  height: 160px;
  cursor: crosshair
}
.hue * {
  user-select: none;
}
.mask {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
}
.saturation {
  background-color: #f00;
}
.white {
  background: linear-gradient(90deg,#fff,hsla(0, 0%, 100%, 0));
}
.black {
  background: linear-gradient(0,#000, transparent);
}
.hue .pointer {
  position: absolute;
  width: 4px;
  height: 4px;
  box-shadow: 0 0 0 1.5px #fff, inset 0 0 1px 1px rgba(0,0,0,.3), 0 0 1px 2px rgba(0,0,0,.4);
  border-radius: 50%;
  transform: translate(-2px,-2px);
}
.slider {
  position: relative;
  width: 200px;
  height: 10px;
  margin: 5px 0;
  cursor: pointer;
  background: linear-gradient(to right, #f00, #ff0, #0f0, #0ff, #00f, #f0f, #f00);
}
.slider .bar {
  height: 10px;
}
.slider .mark {
  position: absolute;
  left: 0;
  width: 4px;
  height: 100%;
}
.slider .mark div {
  margin-top: 1px;
  width: 4px;
  border-radius: 1px;
  height: 8px;
  box-shadow: 0 0 2px rgba(0, 0, 0,.6);
  background: #fff;
  transform: translateX(-2px);
}
.info {
  border: 1px solid #ddd;
  height: 20px;
}